Pulping of nitrocellulose and the like



F. T. B. BONELL PULPING OF NITROCELLULOSE AND THE LIKE April 9, 1957 2 Sheets-Sheet 1 Filed Aug. 22, 1952 FIG.

m v m FRANS TORE BALTZAR BONELL ATTORNEY April 9, 1957 F. T. B. BONELL 2,787,940

PULPING OF NITROCELLULOSE AND THE LIKE med Aug. 22, 1952 2 Sheetsl-Sheet 2 FIG.3

IN VENTOR FRANS TORE BALTZAR BONELL BY Eva-M ATTORNEY PULTING F NITROCELLULOSE AND THE LIKE Frans T. B. Bonell, Stockholm, Sweden, assignor to Aktiebolaget Chematur, Stockholm, Sweden, a corporation of Sweden Application August 22, 1952, Serial No. 305,724

1 Claim. (Cl. 92-20) In the production of nitrocellulose the nitrated fibrous material, usually after preliminary boiling, is introduced into a beater or pulping machine by means of which the nitrocellulose fibers are reduced to the desired degree of fineness to make it possible to extract or neutralise the acid in the fibers by a secondary boiling or poaching.

The beater or pulping machine most generally used has been the Hollander or the Jordan engine of the same type as in the paper and pulp industry. These machines, however do not only cut the fibers into small fragments but have also a squeezing eifect as the fibers or fragments thereof are rolled or compressed between the knives of the machines. This effect is of great importance in the paper industry as the cellulose fibers thereby undergo a fibrillation or hydrating process necessary for the paper formation. in the case of nitrocellulose there is no need of such a process as the nitrocellulose fibers are harder than cellulose fibers and can not be fibrillated in the same way as cellulose. The process consumes a great deal of power.

According to the present invention nitrocellulose is cut into fragments by feeding a suspension of it along knives, suitably at about right angles to the edges of the knives,

v at the same time that other knives with their edges pass the first mentioned edges whereby the fibers are out between the edges. By the choice of suitable velocity of flow and corresponding number of cuttings per unit of time it is possible to obtain any desired length of the fiber fragments in one passage. If the cutting results in long and short fiber fragments the resulting suspension can be screened and the long fragments brought back for a repeated cutting.

With these and other objects to be hereinafter stated, I have illustratively exemplified my invention by the accompanying drawing forming a part of this specification.

Fig. 1 is a longitudinal section through a cutting machine in accordance with my invention.

Fig. 2 is a transverse section through the machine viewed from above.

Fig. 3 is the same transverse section from below.

The suspension of nitrocellulose fiber in about 2-8% concentration depending on its nature (nitrated linters or wood cellulose) is fed for instance by pump or by gravity into the machine through the inlet pipe 1 and passes upwardly into a ring-shaped room 2 with radially arranged guiding bars 3 and knives 4. The knives 4 having protruding parts 7 at the base are inserted in slits in the rings 5 and 6 and held in place by the rings 8a and 8b.

Against the knives 4 rotating knives 9 operate. These knives 9 are in the same manner inserted in slits in the rings 10 and 11 and with their protruding parts 12 held in place by the rings 13a and 13b. The rings 10 and 11 are joined together by guiding bars 14, forming extensions of the knives 9, and fixed on the shaft 15 mounted in the ball or roller bearings 16 and 17. The upper bearing 17 is fixed on the axis 15 as well as in a cylindrical part 18 which by turning by hand can be lowered or elevated. As the axis 15 has axially free movement through the bearing 16 the knives 9 thus can be set more or less against the fixed knives 4. With the proper adjustment of the part 18 respectively the knive 9 is found, the part 18 can be held in position by the locking device 19. To prevent liquid leakage, the axis has a stuifing box 20 where it enters the casing 21 of the machine. It is desirable to introduce water under pressure into the stufling box, for instance into the room 22, to prevent nitrocellulose fibers from entering between the rotating parts.

The knives 9 can be radially arranged as the knives 4 or also, as in Fig. 3, mounted at an angle to the radial direction.

T o prevent fiber clogging in the rooms 23 and 24 it is advantageous especially with regard to safety to introduce water under pressure in these rooms. To hold the water thus introduced as well as the water in the stuffing box, under control it is desirable to use rotameters or the like. The axis 15 etc. is rotated by the belt pulley 25. The rotational velocity and the number of knives are chosen in relation to the velocity of the suspension along the sides of the knives to insure desired length of the fiber fragments.

The number of knives in the rotating and the fixed par-t may be the same, but a difierent number, as in the drawings, may also be used. In the latter case smoother running is obtained.

The guiding and supporting bars 14 as well as the knives may be applied with inclined surfaces thus serving as a pumping wheel for the suspension.

After cutting, the suspension leaves the machine through the outlet 26.

The foregoing description and drawings have reference to what may be considered the preferred or approved form of invention. It is to be understood, however, that I may make such changes in construction and arrangements and combinations of parts, material, dimension etc. as may prove expedient and fall within the scope of the appended claims.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

The method of cutting fibrous nitrocellulose carried in suspension in a liquid which includes the steps of feeding the suspended material along the sides of a plurality of fixed knives past the edges of the knives, cutting the fibres of the suspended material as they pass said edges by rotating knives passing closely adjacent to the edges of said fixed knives, and feeding water under pressure to the gaps between the fixed knives and the rotating knives at the ends thereof to seal the latter against entry of fibrous material.

Great Britain May 19, 1904 Sweden Mar. 10, 1931 

